Nowadays, that should be the FIRST question on a rappers mind. "Who do they have beef with?". When you appear with another apper in a video or on a song, you're showing support for that artist and what they do. Whether you think so or not, that is the case. People tune into BET and see Ja Rule and Kurupt in a rap video together, or turn on the radio and hear Rule and Kurupt on a song together and the first thought is "OK, so Tha Row is down with The Inc". Like Eminem says himself in LTS, when you align yourself with a specific rapper, ESPECIALLY if it's working with them and collaborating with them, you pretty much inherit each others beefs.
Then, again, with me, loyalty is the most important aspect of ANY relationship. So...if I were Kiss, when Ja called me I'd have said no because I know right off the bat that several of my label mates have beef with you. I'm actually kinda surprised that Rule asked Jada to do the song knowing that Jada had been rollin' with Em and crew.
But...that's just my opinion.